I am working on a friend's Blues Jr. When he gave it to me I noticed one of the EL84 power tubes was almost out of the socket. To my eye it looked as though the tube was not pushed in far enough to make contact. The socket was not loose and the tube probably got knocked out of the socket by the power cord after a jam. I tested the tube and found it has a short. I also found a resistor that had scorched the PCB. The schematic identifies it as R47 (470k) and the resistor is also testing bad. I replaced the tube and the resistor and still don't get any sound. Any ideas what to check next?